1. Field of the Invention
The invention relates generally to shutter door assemblies and to fabrication methods therefore.
2. Description of Related Art
A wide variety of shutter door designs of the jalousie type have been developed over the years. These typical shutter doors are provided with a set of vanes pivotally mounted within a rectangular frame to regulate the amount of air or light passing through. Such shutter doors are typically constructed entirely of wood. Attempts have been made to fabricate shutter doors from a plastic material or the like. By constructing the shutter door from a plastic material rather than wood, a lighter and less expensive shutter door may be achieved. Further, a shutter door constructed of lightweight plastic components may be assembled more easily than a shutter door constructed entirely of wood. Thus, whereas a wooden shutter door must typically be assembled at a factory after receipt of an order from a customer, a shutter door constructed of plastic components can be assembled either by a jobber, a retailer, or a customer. Accordingly, rather than experiencing a possibly lengthy wait before receiving an assembled shutter door from a factory, a customer may receive the shutter door more promptly. Further, by allowing the shutter door components to be shipped in disassembled form to a jobber, a retailer, or a customer, rather than in assembled form, shipping costs and storage costs are greatly reduced.
Heretofore, however, no suitable plastic shutter door assemblies have been devised. Conventional plastic shutter door assemblies are often too complicated for easy assembly by a retailer or customer. Special tools or skills may be required to assemble the shutter door. Once assembled, the shutter doors are often insufficiently sturdy and durable to resist common wear and tear, especially where the shutter door is mounted to an exterior of a building and thereby must weather wind, storms, and the like.
Regarding plastic extrusion techniques in general, a wide variety of such techniques have been developed for forming plastic tubes of a variety of shapes and sizes. Typically, such devices employ an extrusion head for extruding a tube of extrudant and a calibrator for cooling the extrudant while maintaining its shape. To form a tube having a circular cross-section, an extrusion head having a circular cross-section is employed in conjunction with a calibrator having a central circular cooling conduit. The circular tube of extrudant is fed into the conduit of the calibrator, where it is cooled. A vacuum system is employed to maintain the tube of extrudant against the inside of the conduit of the calibrator, to thereby maintain the shape of the tube as the tube is cooled. To form a generally rectangular cross-sectional tube, a rectangular extrusion head is employed along with a calibrator having a rectangular cooling conduit. In general, both the shape of the cooling conduit of the calibrator and the shape of the extrusion head must match the cross-sectional shape or profile of the desired tube shape. That is, to form a circular tube, a circular extrusion head and a circular calibrator must be employed. To form a rectangular tube, a rectangular extrusion head and a rectangular calibrator conduit must be employed. Whereas a calibrator may be fairly easily provided with a central conduit having a desired shape, it is often expensive to provide for an extrusion head having an arbitrary desired profile.
To form a shutter door assembly from extruded plastic tubes, a wide variety of sizes and shapes of the tubes must be utilized. Accordingly, a wide variety of extrusion heads and corresponding calibrator conduits must be employed.
Finally, with regard to conventional extrusion techniques, tubes with rectilinear cross-sections formed from conventional extrusion techniques typically have sharp corners. These sharp corners tend to weaken the tube.